Reaction of 4-chloro anthranilic acid 1 with chloroacetyl chloride followed by 4-fluoro aniline provides 7-chloro-2-(chloromethyl)-3-(4-fluorophenyl) quinazolin-4(3H)-one 3, which on treatment with 2-chloro benzimidazole in the presence of potassium carbonate yielded 7-chloro-2-(2-chloro-benzoimidazol-1-ylmethyl)-3-(4-fluorophenyl)-3H-quinazolin-4-one 4. The latter on reaction with nitrogen nucleophiles in acetone containing K2CO3 and catalytic amount of KI gave novel 7-Chloro-3-(4-fluoro phenyl)-2-((substituted amino -1H-benz[d]imidazol-1-yl)methyl) quinazolin-4(3H)-one derivatives 5a-h. Furthermore all the compounds were also tested against Gram negative, Gram positive bacteria and fungi. Among the compound tested in this study, compounds 2-(2-pyrrolidin-1-yl-benzimidazol-1-ylmethyl)-3H-quinazolin-4-one (5b) and 2-(2-piperidin-1-yl-benzimidazol-1-ylmethyl)-3H-quinazolin-4-one (5c) found more potent against S. aureus and E. coli compare to reference standard ampicillin.